1. Technical Field
The present invention relates to an image forming device utilizing an electrophotographic system such as a printer, a copier, a fax machine, or the like. In particular, the present invention relates to an image forming device which forms an image in accordance with a predetermined printing sequence, and which has an image forming engine section which develops an electrostatic latent image, which is formed by charging and exposure by a light beam, and transfers the toner image, which is made visible, from an image carrier onto a transfer member.
2. Related Art
In a conventional monochromatic image forming device using a photosensitive belt as an image carrier, when fluctuations in the speed of photosensitive belt arise, there are the problems that elongation and contraction arise in the finished image such that warping is caused at the image, and in an image having information such as a barcode or the like, that information cannot be read.
In a color image forming device which forms a finished image by superposing two or more colors in a similar structure having a photosensitive belt, there is the fatal problem of color offset between the respective colors increasing due to, in addition to the above-described problem of elongation and contraction and the like of a single-color image, non-uniform rotating speed of the photosensitive belt or a transfer belt.
Fluctuations in the speed of a photosensitive belt tend to arise when the driving load is large. In a color image forming device, the driving load tends to increase even more in particular when there is a structure in which a plurality of developing devices are lined-up at the outer periphery of the photosensitive belt, or when there are members which slidingly-contact the inner and outer peripheral sides of the photosensitive belt without being slave-driven (or while rotating in the opposite direction), or the like.
There are cases in which periodic non-uniformity in the rotating and driving of the drive source itself, e.g., a motor, is caused due to the aforementioned driving load. Further, there are cases in which slight slippage arises between the photosensitive belt and the surface of a driving roller, which is formed of an elastic member and around which the inner peripheral surface of the photosensitive belt is trained and which guides the circulating movement of the photosensitive belt, such that unsystematic non-uniformity of rotation is caused.